1. Field of the Invention
The present invention relates to a connecting structure for covered wires where their respective conductors are connected to each other by oscillating respective insulating covers of the wires with ultrasonic waves. More particularly, it relates to a connecting structure which is effective to connect a shield wire with a ground wire.
2. Description of the Related Art
Generally, it is complicated and troublesome to handle a shield wire having a braided wire coaxially disposed around a core line (or core lines) with the deteriorated workability in using the shield wire. As an effective measure for improving the deteriorated workability, there is provided a connecting structure for wires which takes advantage of inside heating due to the ultrasonic oscillation by Japanese Unexamined Patent Publication (kokai) No. 7-320842.
In the publication, there are shown two kinds of covered wires. One is a shield wire which comprises a core line, an inside insulating rind arranged outside the core line, a braided wire as a shield conductor arranged outside the inside insulating rind, and an outside insulating rind. The other is a ground wire consisting of a core line and an outside resinous rind arranged outside the core line.
According to the disclosed method of connecting the braided wire of the shield wire being connected to a connector, to the core line of the ground wire being also connected to the connector, in front of the connector, the ground wire is firstly overlaid on the shield wire so as to cross each other at a connection point. Next, the overlapping portions are interposed between upper and lower resin tips. Then, while compressing the upper and lower resin tips from the outside, they are subjected to ultrasonic oscillation by making use of an ultrasonic horn and an anvil. Consequently, both of the outside rinds of the shield wire and the ground wire are molten for elimination, so that the braided wire of the shield wire comes into electrical contact with the core line of the ground wire. Simultaneously, the upper and lower resin tips are mutually welded to each other thereby to seal up the surroundings of the above connecting point. In a, in the modification, the upper and lower resin tips are provided on bearing faces, respectively thereof, with wire-accommodating shallow grooves for positioning the shield wire.
However, in the so-obtained connecting structure a tip of the core line of the ground wire sometimes projects from the integrated upper and lower resin tips, so that the connecting part gets larger due to the resultant protrusion, causing an obstacle to arranging the wire harness. In addition, the problem of reduction in the insulating effect arises from the projecting conductor (core line) of the ground wire.
Under such a circumstance, it is therefore an object of the present invention to provide a connecting structure for covered wires, which is capable of preventing a conductor of the covered wire from projecting from the structure.
The object of the present invention described above can be accomplished by a connecting structure for covered wires, comprising:
a first covered wire having a first conductor covered with a first resinous cover;
a second covered wire having a second conductor covered with a second resinous cover, the second conductor being electrically connected with the first conductor of the first covered wire cross each other; and
an upper resin tip and a lower resin tip between which an electrical connecting part of the first and second conductors and the surroundings are interposed, the upper resin tip being welded to the lower resin tip while interposing the first and second covered wires between the upper resin tip and the lower resin tip;
wherein either one of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a stopper as a projection for defining the position of a leading end of the second covered wire interposed between the upper and lower resin tips, while the other of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a recess for receiving the stopper.
With the above-mentioned connecting structure, since the stopper serves to define the tip of the second covered wire in position, there is no possibility that the a tip of the second conductor of the second covered wire projects from the upper and lower resin tips. Therefore, since a protrusion resulting from the projecting second conductor of the second covered wire is eliminated on the peripheral face of the welded resin tips, it is possible to provide the small-sized connecting part between the first and second covered wires, whereby the workability in arranging the wire harness can be improved. Further, with the reduction of an exposed portion of the second conductor, it is possible to improve the insulating effect of the connecting structure.
In the above-mentioned connecting structure, preferably, the first covered wire is a shield wire, while the second wire is a ground wire and the first conductor is a shield conductor of the shield wire, while the second conductor is a core line of the ground wire.
With the preferred structure, as the stopper serves to prevent the core line of the ground wire from projecting from the upper and lower resin tips, it is possible to avoid the exposure of the core line. Thus, also in this case, since a protrusion resulting from the projecting core line of the ground covered wire is eliminated on the peripheral face of the completed connecting part, it is possible to provide the small-sized connecting part between the shield wire and the ground wire, so that the workability in arranging the wire harness can be improved.
In the above-mentioned connecting structure, preferably, the stopper is substantially U-shaped in its plan view to form a groove for fitting the leading end of the second covered wire, the groove being defined by a pair of opposing sidewalls, and a distance between the sidewalls of the groove is smaller than a diameter of the second covered wire.
With the preferred connecting structure, since the leading end of the second covered wire is fitted in the groove of the stopper, it is possible to fix the second covered wire securely. Therefore, the setting operation of the ground wire can be facilitated. Furthermore, as the displacement of ground wire during the welding can be restricted owing to the provision of the stopper, it is possible to improve the electrical reliability of the connecting part.
In the present invention, preferably, each of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a wire receiving groove which has a semi-circular cross section having a diameter substantially equal to a diameter of the first covered wire.
According to the preferred connecting structure, since the diameter of the wire receiving groove is substantially equal to the diameter of the first covered wire, it is possible to weld the upper resin tip to the lower resin tip in the wrapping manner without compressing the first resinous cover of the first covered wire. Thus, since there is no possibility that the first resinous cover of the first covered wire is torn or broken by the upper or lower resin tip, the fixing force between the upper and lower resin tips and the first covered wire can be enhanced. In addition, it is possible to exclude a possibility that the first covered wire exposes the first conductor in the vicinity of the upper and lower resin tips.
According to the present invention, there is also provided a method of producing a connecting structure for covered wires, the method comprising the steps of:
preparing a first covered wire having a first conductor covered with a first resinous cover and a second covered wire having a second conductor covered with a second resinous cover;
overlaying the second covered wire on the first covered wire cross each other;
interposing respective overlapping portions of the first and second covered wires between an upper resin tip and a lower resin tip; and
oscillating the upper and lower resin tips with ultrasonic waves while compressing the upper and lower resin tips from the outside, whereby the first and second resinous covers of the first and second covered wires are molten for removal thereby to bring the first conductor of the first covered wire into electrical contact with the second conductor of the second covered and simultaneously, the upper and lower resin tips are mutually welded to each other thereby to seal up the surroundings of a contact between the first conductor and the second conductor;
wherein either one of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a stopper as a projection for defining the position of a leading end of the second covered wire interposed between the upper and lower resin tips, while the other of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a recess for receiving the stopper.
Also in the above-mentioned method, preferably, the first covered wire is a shield wire, while the second wire is a ground wire and the first conductor is a shield conductor of the shield wire, while the second conductor is a core line of the ground wire.
Also in the above-mentioned method, preferably, the stopper is substantially U-shaped in its plan view to form a groove for fitting the leading end of the second covered wire, the groove being defined by a pair of opposing sidewalls, and a distance between the sidewalls of the groove is smaller than a diameter of the second covered wire.
Also in the above-mentioned method, preferably, each of the upper and lower resin tips is provided, on its butt face being abutted against the other resin tip, with a wire receiving groove which has a semi-circular cross section having a diameter substantially equal to a diameter of the first covered wire.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompany drawings.